While visiting his uncle in the Caribbean, Biff Brewster gets caught up in a thrilling hunt for a hidden pearl fishery. After meetinga boy named Derek, who looks strangely identical to Biff, the pair set off on a dangerous adventure across the islands.

Braving treacherous jungles, dodging tropical storms, and escaping poisonous creatures, Biff and Derek follow a trail of cryptic clues. But sinister forces are also searching for the valuable pearl cache. Will the doppelgänger duo unravel the mystery and locate the secret fishery before their rival treasure-seekers? Or will their journey end in disaster beneath the merciless Caribbean sun?